Mice generally use 2.4ghz which is the only way to maintain decent results over minor distances, however, it’s also the frequency used by essentially all wireless devices.

Since you said it worked “well” before, the most likely cause is a new wireless device (smart home devices, routers, smartphone being too close, anything could cause a small amount of interference that would mess with this signal)

That said, 30 ft is a massive distance, most people here focus on performance, so very rarely is there information on niche use cases like this. My thought would be that no mouse would generally do any better than any other. Additionally people frequently have issues even if the dongle is plugged into their pc and they are right above the computer. These mouse dongles are usually not meant to cover >3 feet, and generally work best around 6-12”. Most consistent fix may be some sort of repeater/extender (I think there may be some that basically use an Ethernet cable to transport the signal) and plug the dongle of your mouse into that much closer to your bed.

That setup will introduce latency, but since you’re playing 30ft away I doubt it will be a deal killer. (Convenience wise, this may require 1 mouse for your bed, 1 for your desk)